This invention relates to an improved copper chloride/alkali metal chloride catalyst on silica or titania carrier, for reaction between hydrogen chloride and elemental oxygen generating chlorine and/or chlorinating an organic material containing hydrogen replaceable by chlorine.
Such catalysts are known in general in the prior art, for example, in U.S. Pat. No. 3,210,158 of Oct. 5, 1965 to Engel et al. In that patent a silica gel preferably having average pore diameter of at least 60 Angstroms, e.g. 140 Angstroms in certain examples, and having surface area of at least 200 square meters per gram is impregnated with a solution of the chlorides of copper, one or more rare earth metals and one or more alkali metals. Conventionally, such catalysts are formed by use of aqueous solutions. The impregnated carrier was dried and heated for 3 hours in an air stream to 250.degree. C.
The catalyst was used for conversion of hydrogen chloride into chlorine at space velocities in the examples of 40 liters of gaseous HCl or 80 liters of gaseous HCl per kilogram of catalyst per hour. These space velocities calculate to residence times of about 50 seconds and about 20 seconds, respectively. The proportions of metal compounds and the temperatures employed are such as to assure that the mixture of metal compounds is entirely or partly present in the molten state. The temperatures in the examples are 300.degree. C., 350.degree. C. and 400.degree. C.
U.S. Pat. No. 3,657,367 of Apr. 18, 1972 to R. J. Blake et al. is representative of prior art disclosures showing chlorination of organic materials in the vapor phase by action of hydrogen chloride and an oxygen-containing gas (i.e. the process known as oxyhydrochlorination, or "OHC"). This patent points out that copper halide catalysts are volatile at the required reaction temperature, resulting in loss of activity over an extended period of time and a tendency of the catalyst to cake during its active life. The patent discloses a catalyst of cupric chloride, potassium chloride or sodium chloride, and a mixture of didymium and lanthanum chlorides, whereby the fluidized catalyst does not tend to cake during its active life at the reaction temperatures which are between about 300.degree. and about 600.degree. C., preferably between about 350.degree. and about 450.degree. C. The preferred residence time is about 1 to about 20 seconds, especially about 2 to 10 seconds. The supports or carriers used in this patent have surface area not over 90 square meters per gram, preferably about 1 to about 30 square meters per gram; they include silica gel but preferably are alpha-alumina or silica-alumina.
A catalyst formed from finely divided pyrogenic oxide such as non-porous pyrogenic silica particles, impregnated with an aqueous solution of a metal compound such as molybdenum, chromium, tungsten, cobalt, vanadium, titanium, platinum, nickel and the like, has been disclosed in U.S. Pat. No. 3,235,508 of Feb. 15, 1966 to K. L. Mills. The catalyst is employed for hydrocarbon cracking and for olefin polymerization.